Influence of landscape features on the microgeographic genetic structure of a resident songbird.

Landscape features influence individual dispersal and as a result can affect both gene flow and genetic variation within and between populations. The landscape of British Columbia, Canada, is already highly heterogeneous because of natural ecological and geological transitions, but disturbance from human-mediated processes has further fragmented continuous habitat, particularly in the central plateau region. In this study, we evaluated the effects of landscape heterogeneity on the genetic structure of a common resident songbird, the black-capped chickadee (Poecile atricapillus). Previous work revealed significant population structuring in British Columbia that could not be explained by physical barriers, so our aim was to assess the pattern of genetic structure at a microgeographic scale and determine the effect of different landscape features on genetic differentiation. A total of 399 individuals from 15 populations were genotyped for fourteen microsatellite loci revealing significant population structuring in this species. Individual- and population-based analyses revealed as many as nine genetic clusters with isolation in the north, the central plateau and the south. Moreover, a mixed modelling approach that accounted for non-independence of pairwise distance values revealed a significant effect of land cover and elevation resistance on genetic differentiation. These results suggest that barriers in the landscape influence dispersal which has led to the unexpectedly high levels of population isolation. Our study demonstrates the importance of incorporating landscape features when interpreting patterns of population differentiation. Despite taking a microgeographic approach, our results have opened up additional questions concerning the processes influencing dispersal and gene flow at the local scale.

Predicting spatial patterns of eagle migration using a mesoscale atmospheric model: a case study associated with a mountain-ridge wind development.

High resolution numerical atmospheric modeling around a mountain ridge in Northeastern British Columbia (BC), Canada was performed in order to examine the influence of meteorology and topography on Golden Eagle migration pathways at the meso-scale (tens of km). During three eagle fall migration periods (2007-2009), local meteorological conditions on the day of peak bird counts were modeled using the Regional Atmospheric Modeling System (RAMS) mesoscale model. Hourly local surface wind speed, wind direction, temperature, pressure and relative humidity were also monitored during these migration periods. Eagle migration flight paths were observed from the ground and converted to three-dimensional tracks using ArcGIS. The observed eagle migration flight paths were compared with the modeled vertical velocity wind fields. Flight tracks across the study area were also simulated using the modeled vertical velocity field in a migration model based on a fluid-flow analogy. It was found that both the large-scale weather conditions and the horizontal wind fields across the study area were broadly similar on each of the modeled migration days. Nonetheless, the location and density of flight tracks across the domain varied between days, with the 2007 event producing more tracks to the southwest of the observation location than the other 2 days. The modeled wind fields suggest that it is not possible for the eagles to traverse the study area without leaving updraft regions, but birds do converge on the locations of updrafts as they move through the area. Statistical associations between observed eagles positions and the vertical velocity field suggest that to the northwest (and to a lesser extent the southwest) of the main study ridge (Johnson col), eagles can always find updrafts but that they must pass through downdraft regions in the NE and SE as they make their way across the study area. Finally, the simulated flight tracks based on the fluid-flow model and the vertical velocity fields are in general agreement with the observed flight track patterns. Our results suggest that use of high resolution meteorological fields to locate the occurrence of updrafts in proposed ridge-line wind installations could aid in predicting, and mitigating for, convergence points in raptor migrations.

Failure to detect seasonal changes in the song system nuclei of the black-capped chickadee (Poecile atricapillus).

Most temperate songbird species sing seasonally, and the brain areas involved in producing song (the song system) vary in size alongside the changes in behavior. Black-capped chickadees (Poecile atricapillus) also sing seasonally, and we find that there are changes in the stereotypy and the length of the fee-bee song from the nonbreeding to the breeding season. Yet despite these changes, we fail to find any evidence of seasonal changes in the song system. The song system of males is larger than that of females, as is typical in songbirds, but the ratio between the sexes is small compared to other species. We suggest three hypotheses to explain our failure to find seasonal variation in the chickadee song system.

Surveillance of antimicrobial resistance of invasive pathogens: the Estonian experience.

The aim of the present study was to evaluate the needs for surveillance of invasive Gram-negative pathogens in Estonia. The antimicrobial susceptibility data of invasive isolates of Acinetobacter baumannii, Pseudomonas aeruginosa, Klebsiella spp, Escherichia coli, Staphylococcus aureus, Streptococcus pneumoniae and enterococci were collected in accordance with EARSS (European Antimicrobial Resistance Surveillance System) protocols. Despite the higher rate of Gram positive pathogens, their resistance to antimicrobials was low in contrast to the elevated resistance established for Gram negative pathogens. The higher resistance to antimicrobials was particularly associated with A. baumannii and P. aeruginosa. Also, the proportion of extended spectrum betalactamase (ESBL)-producing strains was 23% among Klebsiella spp. and 3.6% among E. coli. The inclusion of invasive Gram negative pathogens in antimicrobial resistance surveillance provides useful information concerning local pathogen susceptibility, as well as for the empirical treatment of suspected infections.

Surveillance of antimicrobial resistance of invasive pathogens: the Estonian experience.

The aim of the present study was to evaluate the needs for surveillance of invasive Gram-negative pathogens in Estonia. The antimicrobial susceptibility data of invasive isolates of Acinetobacter baumannii, Pseudomonas aeruginosa, Klebsiella spp, Escherichia coli, Staphylococcus aureus, Streptococcus pneumoniae and enterococci were collected in accordance with EARSS (European Antimicrobial Resistance Surveillance System) protocols. Despite the higher rate of Gram positive pathogens, their resistance to antimicrobials was low in contrast to the elevated resistance established for Gram negative pathogens. The higher resistance to antimicrobials was particularly associated with A. baumannii and P. aeruginosa. Also, the proportion of extended spectrum betalactamase (ESBL)-producing strains was 23% among Klebsiella spp. and 3.6% among E. coli. The inclusion of invasive Gram negative pathogens in antimicrobial resistance surveillance provides useful information concerning local pathogen susceptibility, as well as for the empirical treatment of suspected infections.

Pharmacokinetics of morphine 3-esters after oral administration in rabbits.

Pharmacokinetics of three morphine 3-esters-3-(2,2-dimethylvaleroyl) morphine (A), 3-(2-phenylbenzoyl) morphine (B), and 3-(2,2-diphenylpropionyl) morphine (C) was characterized after single oral administration in rabbits. Blood was sampled up to 24 h and cerebro-spinal fluid (CSF) was collected with the last blood sample. The concentration of the morphine 3-esters, morphine, morphine 3-glucuronide and morphine 6-glucuronide were determined in plasma and CSF using HPLC UV-detection. The morphine 3-esters were suggested to be a subject to marked presystemic elimination, since, in comparison to the administration of the un-esterified morphine, relatively low concentrations of morphine and morphine glucuronides were detected in plasma. The rate of disposition of morphine was dependent on the hydrolytic stability of the esters. The mean (+/- S.E.) plasma half-life of morphine was 0.9 +/- 0.2 h, 2.5 +/- 0.6 h and 3.5 +/- 3.5 h after the administration of A, B and C, respectively, compared to 0.9 +/- 0.2 h as estimated after the administration of non-esterified morphine. An analgesic effect will be achieved, since morphine was detected in CSF even 24 h after the application of the ester pro-drugs. It is concluded that esterification at the 3-position may be adapted to obtain sustained plasma levels of morphine.

[Determination of pravastatin in rat liver by RP-HPLC].

AIM: To establish a reverse-phase high performance liquid chromatographic method for the determination of pravastatin in rat liver. METHODS: An aliquot of 5 g liver homogenates, spiked with triamcinolone acetonide (internal standard), was extracted by solid-phase extraction with Bond Elut C18 columns. Chromatography was performed using a C18 reverse-phase column with mobile phase of Na2HPO4 buffer sdution (0.035 mmol.L-1, pH 3.0)-acetonitrile (155:42). RESULTS: The linear equation was Y = 0.1843X-4.238 x 10(-3) (gamma = 0.9934) in the range of 0.05-10 micrograms.g-1 liver. The limit of detection for pravastatin was 13 ng.mL-1 (signal-to-noise ratio of 3), and the limit of quantification for pravastatin in liver homogenate was 50 ng.g-1 liver (RSD < 20%). The average extraction recovery of pravastatin from liver at different concentrations was 80.8%, and the average inter-day precision was 11%. This procedure was applied to assay pravastatin in rat liver which were collected from Lewis rats at different times after administration of pravastatin (ig 20 mg.kg-1). CONCLUSION: The method was sensitive and is feasible for the pharmacokinetic and distribution study of pravastatin.

Determination of morphine 3-esters in rabbit plasma by high-performance liquid chromatography with ultraviolet detection.

A sensitive high-performance liquid chromatographic (HPLC) method for the quantitation of the morphine 3-esters 1[3-(2, 2-dimethylvaleroyl)-morphine (A), 3-(2-phenylbenzoyl)-morphine (B) and 3-(2,2-diphenylpropionyl)-morphine (C)] in rabbit plasma is described. Sample preparation was based on reversed-phase solid-phase extraction. The compounds were separated on C(18) reversed-phase analytical columns and then determined by ultraviolet detection. The recovery from plasma was 78.7 +/- 7.4%, 69.1 +/- 6.9% and 75 +/- 7.2% (mean +/- SD) for A, B, and C, respectively. The present method enabled the detection limit of 0.2, 0.2 and 0.1 ng and quantification limit of 20, 10 and 10 ng/ml for A, B and C, respectively. The developed method was used for determination of the plasmakinetics of these morphine 3-esters in rabbits.

Variation with age in the pattern of type X collagen expression in normal and scoliotic human intervertebral discs.

The distribution and expression of type X collagen, a calcium-binding collagen, which is a marker of hypertrophic chondrocytes and thought to be involved in cartilage calcification, was examined in situ in nondegenerate (grade I or II) human discs taken at autopsy over a wide age range (fetal->80 years) and also in scoliotic discs removed at surgery. In the fetal vertebral column, type X collagen was strongly expressed in the hypertrophic chondrocytes of the endplate, but was not seen in other areas. In the cartilaginous endplate of adults, it was found over the whole age range examined, with intensity increasing with age. In the disc matrix itself, type X collagen was demonstrated around individual cells from all individuals older than 50 years, but not in any fetal or autopsy disc from individuals younger than 40 years. In scoliotic discs, however, focal type X collagen expression was seen in 3/8 patients younger than 40 years including one 12-year-old. No type X collagen was found in the outer annulus in any autopsy or scoliotic disc, supporting the idea that cells of the outer annulus are phenotypically distinct from cells of the inner annulus and the nucleus. Our results demonstrate for the first time that type X collagen is a possible gene product of the intervertebral disc cells and a potential biochemical component of the disc matrix. They indicate that with age or in scoliosis, some cells from the inner annulus or nucleus of the disc differentiate to the hypertrophic chondrocyte phenotype. This might be the initiating event for the abnormal calcification described in aged and scoliotic discs in other studies.

Determination of pravastatin in human plasma by high-performance liquid chromatography with ultraviolet detection.

A sensitive high-performance liquid chromatographic (HPLC) method for the quantitation of the HMG-CoA reductase inhibitor pravastatin in human plasma is described. Sample preparation based on reversed-phase solid-phase extraction using triamcinolone acetonide as internal standard (I.S.). The compounds were separated on C18 reversed-phase analytical column and then determined by ultraviolet detection. The recovery of pravastatin from plasma was 69.2+/-6.7% (mean+/-S.D.). The limit of detection for pravastatin in aqueous solution was 0.4 ng, the limit of quantitation in plasma was 2 ng/ml. In a preliminary pharmacokinetic study with two healthy volunteers the t1/2 of pravastatin in plasma was found to be 0.8 and 2.3 h.